In bioclimatology, the state of air environmental condition is called by scientific workers as the aerosol state. Molecule cluster, liquid and solid particles dispersed in air as aerosols are mostly nanoparticles.
Nanoparticles exhibit small-scale effect, surface and interfacial effect and quantum-scale effect, and have large specific surface area and big number of atoms on the surface. Surface effect and interfacial effect are intensified with decreasing particle size. The big specific surface area and the big number of atoms on the surface increase the activity of the nanoparticle greatly. Due to the small-scale effect and surface effect, nanoparticles of different size also cause variation of surface electron spin conformation and electron energy spectra distribution. Quantum-scale effect of nanoparticles results in discrete energy level. The interval between energy levels changes with the changes of the nanoparticle sizes. Nanoparticles in aerosol are composed of different particles with different sizes. Because of the above-mentioned properties, nanoparticles greatly enhanced the ability to combine with electrons of different energy levels to form a very wide energy band of electron affinity.
The problem is what kind of electron-emitting electrode can be used to achieve a strong enough electric field with narrowing potential barrier on the electrode surface. Due to the tunnel effect in quantum mechanics, electrons will penetrate and escape from the tunnel as field electron emission. How to increase the emission current density is a problem under research.
In the 1960s, electrically charged aerosol centers were established in Texas and other states in the US. By ejecting pressurized gas the atomized physiological saline and electrons were emitted at the same time in the same direction at an electric potential of 26 kV-60 kV on an ejector to form electrically charged aerosol. Such aerosol was used to cure respiratory disease. It was effective in curing bronchitis and asthma, infection of the upper respiratory tract, emphysema, laryngitis, and pharyngitis. Besides the ejector, auxiliary equipments of gas pump, and liquid transport system were required. Atomized saline particles were mostly not nanoparticles. Even under the action of 26 kV-60 kV electric field, electrically charged aerosol could only travel a distance of about 1.8 m and disappeared beyond that distance. Such electrically charged aerosol was not able to directly participate in the electric metabolism at the tissue-cell-molecule level, so the biological effect and sterilizing effect were less promising.